An electrowetting display is an image display system in which a plurality of pixels each filled with two phases, i.e., an aqueous medium and an oil-based coloring ink, is disposed on a substrate and the affinity at the aqueous-medium/substrate interface is controlled for each pixel by means of voltage application on-off switching to cause the oil-based coloring ink to spread/agglomerate on the substrate and thereby display an image (non-patent document 1). Colorants for use in electrowetting displays are required to have, for example, high solubility in lowly polar solvents (patent document 1 and patent document 2).
In patent documents 3 to 6 are shown dye colorants for polyester fibers, the dye colorants including a disazo compound having excellent fastness properties. In patent document 7 are shown a cyan colorant which is for use in thermal transfer sheets and which readily undergoes sublimation and/or thermal diffusion and an ink composition that employs the colorant. Media for ink preparation are mentioned therein.